1. Field of the Invention
This invention relates to the equalization of high frequency video signals and, more particularly, to voltage controlling the equalization of high frequency video signals.
2. Description of Related Art
Equalization of high frequency signals typically involves, as a basic requirement for the ideal transmission channel, an ability to transmit the signal over a range of frequencies without introducing gain, or amplitude, or phase changes that are dependent on the frequency of the transmitted signal. In that ideal system, one could, in theory, avoid a frequency dependent distortion of the signal. However, the ideal channel does not exist and, consequently, to obtain an accurate replica of the original signal upon its reception or reproduction, it is necessary to compensate for distortion in the signal. The compensation process is known as equalization.
Voltage controlled equalizers for equalization of signals transmitted over a channel having a non-uniform frequency response are known in the art. See, for example, U.S. Pat. No. 4,633,200 issued Dec. 30, 1986.
High frequency video signals can also be equalized by networks comprising various combinations of resistors (R) and capacitors (C). While there are RC networks, which are known to equalize video signals, they typically increase the differential phase and differential gain distortion of the equalized video signals to unacceptable levels.
Accordingly, it is an object of the present invention to achieve the high frequency equalization needed by video signals while greatly reducing the differential phase and the differential gain distortion that are typically associated with known equalization embodiments, which operate on video signals.